xref: /openssl/doc/man3/SSL_get_ciphers.pod (revision 4746f25a)
1=pod
2
3=head1 NAME
4
5SSL_get1_supported_ciphers,
6SSL_get_client_ciphers,
7SSL_get_ciphers,
8SSL_CTX_get_ciphers,
9SSL_bytes_to_cipher_list,
10SSL_get_cipher_list,
11SSL_get_shared_ciphers
12- get list of available SSL_CIPHERs
13
14=head1 SYNOPSIS
15
16 #include <openssl/ssl.h>
17
18 STACK_OF(SSL_CIPHER) *SSL_get_ciphers(const SSL *ssl);
19 STACK_OF(SSL_CIPHER) *SSL_CTX_get_ciphers(const SSL_CTX *ctx);
20 STACK_OF(SSL_CIPHER) *SSL_get1_supported_ciphers(SSL *s);
21 STACK_OF(SSL_CIPHER) *SSL_get_client_ciphers(const SSL *ssl);
22 int SSL_bytes_to_cipher_list(SSL *s, const unsigned char *bytes, size_t len,
23                              int isv2format, STACK_OF(SSL_CIPHER) **sk,
24                              STACK_OF(SSL_CIPHER) **scsvs);
25 const char *SSL_get_cipher_list(const SSL *ssl, int priority);
26 char *SSL_get_shared_ciphers(const SSL *s, char *buf, int size);
27
28=head1 DESCRIPTION
29
30SSL_get_ciphers() returns the stack of available SSL_CIPHERs for B<ssl>,
31sorted by preference. If B<ssl> is NULL or no ciphers are available, NULL
32is returned.
33
34SSL_CTX_get_ciphers() returns the stack of available SSL_CIPHERs for B<ctx>.
35
36SSL_get1_supported_ciphers() returns the stack of enabled SSL_CIPHERs for
37B<ssl> as would be sent in a ClientHello (that is, sorted by preference).
38The list depends on settings like the cipher list, the supported protocol
39versions, the security level, and the enabled signature algorithms.
40SRP and PSK ciphers are only enabled if the appropriate callbacks or settings
41have been applied.
42The list of ciphers that would be sent in a ClientHello can differ from
43the list of ciphers that would be acceptable when acting as a server.
44For example, additional ciphers may be usable by a server if there is
45a gap in the list of supported protocols, and some ciphers may not be
46usable by a server if there is not a suitable certificate configured.
47If B<ssl> is NULL or no ciphers are available, NULL is returned.
48
49SSL_get_client_ciphers() returns the stack of available SSL_CIPHERs matching the
50list received from the client on B<ssl>. If B<ssl> is NULL, no ciphers are
51available, or B<ssl> is not operating in server mode, NULL is returned.
52
53SSL_bytes_to_cipher_list() treats the supplied B<len> octets in B<bytes>
54as a wire-protocol cipher suite specification (in the three-octet-per-cipher
55SSLv2 wire format if B<isv2format> is nonzero; otherwise the two-octet
56SSLv3/TLS wire format), and parses the cipher suites supported by the library
57into the returned stacks of SSL_CIPHER objects sk and Signalling Cipher-Suite
58Values scsvs.  Unsupported cipher suites are ignored.  Returns 1 on success
59and 0 on failure.
60
61SSL_get_cipher_list() returns a pointer to the name of the SSL_CIPHER
62listed for B<ssl> with B<priority>. If B<ssl> is NULL, no ciphers are
63available, or there are less ciphers than B<priority> available, NULL
64is returned.
65
66SSL_get_shared_ciphers() creates a colon separated and NUL terminated list of
67SSL_CIPHER names that are available in both the client and the server. B<buf> is
68the buffer that should be populated with the list of names and B<size> is the
69size of that buffer. A pointer to B<buf> is returned on success or NULL on
70error. If the supplied buffer is not large enough to contain the complete list
71of names then a truncated list of names will be returned. Note that just because
72a ciphersuite is available (i.e. it is configured in the cipher list) and shared
73by both the client and the server it does not mean that it is enabled (see the
74description of SSL_get1_supported_ciphers() above). This function will return
75available shared ciphersuites whether or not they are enabled. This is a server
76side function only and must only be called after the completion of the initial
77handshake.
78
79=head1 NOTES
80
81The details of the ciphers obtained by SSL_get_ciphers(), SSL_CTX_get_ciphers()
82SSL_get1_supported_ciphers() and SSL_get_client_ciphers() can be obtained using
83the L<SSL_CIPHER_get_name(3)> family of functions.
84
85Call SSL_get_cipher_list() with B<priority> starting from 0 to obtain the
86sorted list of available ciphers, until NULL is returned.
87
88Note: SSL_get_ciphers(), SSL_CTX_get_ciphers() and SSL_get_client_ciphers()
89return a pointer to an internal cipher stack, which will be freed later on when
90the SSL or SSL_SESSION object is freed.  Therefore, the calling code B<MUST NOT>
91free the return value itself.
92
93The stack returned by SSL_get1_supported_ciphers() should be freed using
94sk_SSL_CIPHER_free().
95
96The stacks returned by SSL_bytes_to_cipher_list() should be freed using
97sk_SSL_CIPHER_free().
98
99=head1 RETURN VALUES
100
101See DESCRIPTION
102
103=head1 SEE ALSO
104
105L<ssl(7)>, L<SSL_CTX_set_cipher_list(3)>,
106L<SSL_CIPHER_get_name(3)>
107
108=head1 COPYRIGHT
109
110Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
111
112Licensed under the Apache License 2.0 (the "License").  You may not use
113this file except in compliance with the License.  You can obtain a copy
114in the file LICENSE in the source distribution or at
115L<https://www.openssl.org/source/license.html>.
116
117=cut
118